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S. E. RUBBINS.

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@attra-gratta atent @Hirn S. E. ROBBINS, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO ELMER TOWNSEND, OF SAME PLACE.

Letters Patent No. 67,454, dated August 6, 1867.

IMPROVEMENT Ihl PLATFORM-SCALES.

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TO ALL WHOM IT MAY OONCERN:

Be itknown that I, S. E. ROBBINS, of Boston, in the county of Suffolk, and State of Massachusetts, have invented an Improvement in Platform-Scales; 4and I do hereby declare that the following, taken in connection with the drawings which accompany and form part of this specification, is a description ofmy invention sufficient to enable those skilled in the art to practise it.

This invention is, to some extent, in the nature of an improvement upon the construction shown in R. Il `Wolcotts patent of November 1, 1859, the improvement relating to the construction of the various movable knife-edge and socket bearings, or connections between the scale and the supports of the weight-receiving platform, the object of the improvement being to steady the platform, or prevent it from swaying laterally when a heavy body is upon it, and to more eiectually equalize and neutralize the connections throughout the scale. These hearing edges are ordinarily made straight, and rest upon concave seats; and my invention consists in making each knife edge concave, and to rest upon a concave-convex bed-plate or bearing, which, while permitting the edge to rock in a direction at right angles to it, insures a freedom from lateral vibrating sway.

The drawings represent those parts of a platform-scales or weighing apparatus with which my invention is directly connected, A showing a. plan of one-half the frame or bed, forming the base of the platform, B, a section on the line :e x of fig. l.

a a denote the two longitudinal beams of the platform; b, one of the end beams; c, the apparatus; d, the bed or superstructure for supporting the platform. On this bed d are socketssteps d', upon which rest rocking bearings e, as shown in said Wolcotts patent, these bearings forming the stationary supports for the outer fulcra of the system of levers,.through which the weight upon the platform tends to swing the shale-beam. The platform-beams a a have* fixed to their under sides socket-pieces f, into which enter socket-shoes, the lower surfaces of which rest upon knife-edge bearings on the upper side of arms g, projecting from the inner side of a. rocker-shaft, h, at whose outer side are similar 'arms t', upon the lower side of which are knife-edges k, resting upon the outer fulcra l, before referred to, the weight of any body upon the platform depressing the series of arms, and the rocker-shaft. This shaft has fixed upon and extending inwards from it a lever or arm, m, con` nected at its inner end, through a link or hook, i, to a lever,ro, whose inner end is fulcrumed on a step-plate, p, projecting from the platform-beam, and whose outer end is connected, by a rod, 71,to the scale-beam; at all these bearing points, making up the connections between the platform and the scale-beam, andwhere one part has a movement relatively to the other by thc iniiuencc of the weight upon the platformone of the contact edges is made angular in section, or as a knife-odge; and instead of forming this abutting edge straight, I form.

it concave in the direction of its length, and malte the corresponding surface, upon or against which it rests, convex. This construction is shown Vparticularly at B, the section being taken direct-ly through the centres of the two outer fulcra Z and the knife-edges c resting thereupon, similar concave and convex surfaces to those there seen being found at all the similar connections.

By having this construction throughout, all tendency of the knife-edges to slip lengthwise, under any tendency to lateral or vibratory movement of the weight upon the platform, is counteracted, the concave edges settling down at oncc into stationary position as soon as the levers have moved into position in accordance with the weight of the body upon the scales. It will be obvious that this construction obviates, to a great degree, the tendency ofthe beam to vibrate under any lateral movements of the weight upon the scales, and also lessons very materially the wear caused in the common construction by friction of the straight sliding knife-edgesin slipping to and fro upon the surfaces against which they bear. Such wear soon impairs the nicety of movement ofthe levers, while in this construction the accuracy of the scale is much more certain, and the connections are much more enduring. It also avoids the settling and coilection of dirt or dust upon the under bearings, which bearings of necessity are always kept clean and smooth by the action of the concave bearing knife-edgest I claim the construction of the knife-edge bearings throughout the scale with concave edges fitting upon convex surfaces, as and for the purpose substantially as set forth.

S. E. ROBB INS,

Witnesses:

J. B. Onosnv, FRANCIS GOULD. 

